Embodiments relate to a method of fabricating a metal oxide silicon field effect transistor (MOSFET) and a device thereof. Some embodiments relate to a gate of a trench type MOSFET device and a method of forming a gate.
Power MOSFET devices may be used in various electronic devices including a notebook PC, a battery pack, a digital camera, a desk top PC, an LCD monitor, a B/L inverter, a graphic card, and the like. Power MOSFET devices may include, for example, relatively high switching speed, high thermal stability, high power gain in high input impedance, and/or convenience of use. Power MOSFET devices may employ a trench type MOSFET structure in which a buried gate may be formed by forming a trench substantially perpendicular to a substrate instead of an existing horizontal gate, growing an oxide film on and/or over a sidewall of a trench, and/or filling a trench with polysilicon to hold a high voltage and/or regulate a relatively large current.
Referring to FIG. 1, a trench type MOSFET device may include a structure in which a gate poly may be buried in the form of a trench on and/or over a substrate. A trench type MOSFET may be advantageous for relatively high integration since a size of a MESA area connected to a source may be minimized. However, in a trench type MOSFET device, a relatively high electric field may be applied to a gate poly in a structure using a deep trench gate, which may cause an overcurrent to flow through a MOS channel around a gate. Therefore, substantial destruction of a gate oxide film and/or leakage due to an overcurrent flowing through a MOS channel may occur.
Accordingly, there is a need for a method of manufacturing a device and a device thereof that may maximize device reliability. There is a need for a method of manufacturing a device and a device thereof that may, for example, substantially uniformly form an electric field in a MESA area surrounding a gate in a trench type power MOSFET device and/or which may substantially prevent an overcurrent from flowing into a MOS channel around a gate.